Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in the present disclosure and are not admitted to be prior art by inclusion in this section.
Often, a microphone picking up an intended audio signal will also be subjected to other undesirable audio signals. For example, while picking up speech of a user of a handheld phone, a microphone of the handheld phone can also pick up background chatter of other conversations, fan noise of nearby electronic devices, and other interference audio signals of a noisy environment. Moreover, intensities and/or directions of intended (target) audio signals and unintended interference audio signals may change over time.